1. Field of the Invention
This invention relates generally to heat exchanger and water heater apparatus, and more particularly to an eddy current heat generator utilizing a permanent magnet rotatably mounted in a fixed ferrous metal pipe inside a working fluid reservoir with the working fluid being conducted through a heat pipe to heat a second fluid (liquid, air or gas).
2. Brief Description of the Prior Art
Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank of the water heater. A substantial part of the heat that is generated is wasted, and this waste of energy has become increasingly undesirable due to the increasing costs of gas and electricity.
Electric water heaters that utilize electric resistive heater strips or heating elements are highly inefficient, and costly to operate in the long run. Gas water heaters are also inefficient since a significant portion of the heat escapes through the flue.
The use of electromagnetic induction heating of a liquid, and the use of permanent magnets or electromagnets for water "treatment", rather than heating is known in the art. There are several patents which disclose various apparatus that utilize permanent magnets in generating an eddy current for heating a liquid, most of which are cost-prohibitive complex structures, and some of which are unsafe for use.
Hagerty, U.S. Pat. No. 4,217,475 discloses a device for transferring heat to liquids which utilizes a first set of permanent magnets arranged in a circle inside a housing, a second set of magnets mounted on a rotating shaft spaced from the first set, with two concentric conductive sleeves located in the magnetic field between the two sets of magnets. The magnetic field causes the sleeves to be heated by induction. The shaft is rotated by a motor. Fluid is passed through the space between the two sleeves and is heated by heat transferred by the sleeves.
de Bennetot, U.S. Pat. No. 4,486,638 discloses a device for converting rotational energy to heat by generating eddy currents which utilizes permanent magnets attached to a rotatable shaft inside of a fixed cylindrical casing of low electrical resistivity (e.g. copper). Fluid flows through a helical conduit between the magnets and the casing and becomes heated.
Gerard, U.S. Pat. No. 4,511,777 discloses a permanent magnet thermal energy system which utilizes permanent magnets attached to a rotatable shaft inside of a duct. The magnets are attached to a disk rotated by a motor which is positioned adjacent a heat absorber plate (copper). A conductive ferromagnetic plate is connected on the other side of the heat absorber plate and has a series of fins disposed in the path of the fluid (air, gas, or liquid) to be heated.
Fichtner et al, U.S. Pat. No. 4,600,821 discloses a device for converting rotational energy to heat by generating eddy current which utilizes a first set of permanent magnets arranged in a circle on a cylindrical driver inside a housing, a second set of magnets mounted on a rotating shaft (rotor) spaced from the first set. The rotor is driven by the driver in response to attraction by both sets of magnets. A wall made of low electrical resistance material separates the driver and rotor and fluid is passed through the housing over a surface of the separating wall and is heated.
Gerard et al, U.S. Pat. No. 4,614,853 discloses a permanent magnet steam generator which utilizes a dual system of magnets attached to rotatable disks with copper heat absorber plates and conductive ferro-magnetic plates similar to his previous U.S. Pat. No. 4,511,777 that are connected in opposed relation to a boiler through which liquid to be heated is passed.
Gerard, U.S. Pat. No. 5,012,060 discloses a permanent magnet thermal generator which utilizes a first set of permanent magnets arranged in a circle inside a housing, a second set of magnets mounted on a rotor spaced from the first set and having an impeller mounted at one end which conducts fluid to be heated between the magnets.
The present invention is distinguished over the prior art in general, and these patents in particular by a permanent magnet eddy current heat generator apparatus having a thermally insulated working fluid reservoir containing a working fluid and an enlongate stationary ferrous metal tube disposed in the reservoir with an elongate permanent magnet rotatably mounted inside the tube that, upon rotation, causes the tube to become heated due to the eddy current generated in the tube side wall and the heat from the tube side wall is transferred to the working fluid in the reservoir. An elongate working fluid heat pipe has a first end connected with a working fluid reservoir outlet and a second end connected with a reservoir inlet. The elongate permanent magnet is rotated by the shaft of a motor electrically and magnetically insulated from the working fluid and elongate permanent magnet. A pump, also driven by the motor shaft, is connected in fluid communication between the working fluid reservoir outlet and the heat pipe to conduct working fluid in a closed loop from the reservoir, through the heat pipe, back into the reservoir, and around the exterior of the ferrous metal tube. The heat pipe is placed in heat exchange relation in a second fluid (liquid, air or gas) to be heated, such as in a hot water tank, and the heat of the working fluid conducted through the heat pipe is transferred through the heat pipe side wall to heat the second fluid.